In a conventional magnetic recording and/or reproducing apparatus, particularly in a magnetic recording and/or reproducing apparatus having a rotatable magnetic head, the magnetic tape loading mechanism is used to lead a magnetic tape out of a cassette and enable the magnetic tape to be wound onto a rotatable magnetic drum such that information can be recorded on the magnetic tape or reproduced from the magnetic tape by means of the magnetic head. As well known, in a tape-loading process, the magnetic tape has to fulfill the following three conditions such that it may move stably and the magnetic tape loading mechanism may accurately perform various work modes in accordance with a specified time sequence. These conditions include: (a) parallelism condition--the magnetic tape has to move parallel to a datum plane during the period when it is led out of a tape cassette and caused to be wound around a magnetic head; (b) twist condition--there will be no twist when the magnetic tape moves and after it is wound around the magnetic head; and (c) height condition--the center line of the magnetic tape must be maintained at the same height both in the inlet side where the magnetic tape moves toward the inclination post and in the outlet side where the tape moves away from the inclination post. Accordingly, the tape loading mechanism basically includes a moving post and inclination posts for leading a magnetic tape out of a tape cassette and for guiding the tape to move stably, a pinch roller and a capstan shaft for controlling the movement of the magnetic tape, and a tension post for adjusting the tension of the magnetic tape. These members can be actuated to move to the specified positions according to a time sequence set by the unloading, search and stop, and play modes of the magnetic recording and/or reproducing apparatus. However, the known tape loading mechanisms usually comprise a number of links and cam plates or rotating rings, and in each work mode the same link is arranged to simultaneously drive a plurality of post members mentioned above so that these post members can be set in different movement states and moved to different positions to match with various time sequences and work modes. Such a driving method may involve the disadvantages of necessitating a lot of components, a complicate construction, difficulty of design, assembly and maintenance, a higher manufacturing cost, and being easily out of order. Moreover, the overall height of the apparatus is larger as a clearance is required between two links to enable them to be folded on top of another when using links as the driving members. On the other hand, the width, length and thickness of the apparatus will all be increased if the rotating rings are used as driving members, which will not only lead to an increment in the weight of the apparatus but also the difficulty of a compact design.
In view of the aforementioned drawbacks, one object of this invention is to provide a magnetic tape loading mechanism for a magnetic recording and/or reproducing apparatus in which the operational sequence of the moved members can be accurately controlled to enable the same to move smoothly and positively.
Another object of this invention is to provide a magnetic tape loading mechanism for a magnetic recording and/or reproducing apparatus which has an improved movement accuracy and reliability in that the accurate positioning of its moved members can be achieved in a simple and fast manner.
The further object of this invention is to provide a magnetic tape loading mechanism for a magnetic recording and/or reproducing apparatus which is compact in size and simple in construction.